Explosive desorption induced by radical–radical interaction in methane-doped Ar matrices

Abstract

Delayed explosive desorption of particles from Ar matrices highly doped with CH4 stimulated by an electron irradiation was studied using emission spectroscopy methods. The recorded cathodoluminescence (CL) spectra of CH4-containig Ar matrices revealed following products of radiation-induced CH4 transformation: H, CH and C. Three series of experiments were performed with different irradiation and heating modes: (i) continuous irradiation at low temperature with accumulation of radiolysis products, (ii) heating of the pre-irradiated films with measurements of relaxation emissions, specifically thermally stimulated exoelectron emission (TSEE) and (iii) external heating of the pre-irradiated films under beam. These measurments of the, so called, nonstationary luminescenve (NsL) at the selected wavelenghs and nonstationary desorption (NsD) in combination with TSEE recorded provided an information on reactions of charged and neutral species of interest. Taking into account that the CH radical can be considered as a signature of the CH3 species [27] we obtained the information on a role of H atoms and CH3 radicals in stimulation of explosive delayed desorption of particles from Ar matrices doped with CH4. Two bursts of long-period self-oscillations together with short-period ones with a limited number of periods were observeed during stationary irradiation of all CH4-doped Ar matrices at low temperatures. Processes leading to the self-oscillations of particle yield are discussed.